The invention relates to a speed control assembly for a motor or engine, in general, and more particularly to a control of a hydrostatic transmission of a motor vehicle. The control assembly according to the present invention is simple and conveniently operated, and the force required to effect control is relatively low. Additionally, the speed control provides in a simple manner for an infinite speed selection within its limits of travel, and for safety when utilized with a motor vehicle--the control assembly ensures automatic return to neutral when the brakes are applied or the driver's seat is vacated. The internal frictional drag of a hydrostatic unit is such that when in neutral it can bring a vehicle to approximate rest without brakes, and thus when the control assembly according to the present invention is utilized with a hydrostatic transmission it provides a further degree of safety.
According to one aspect of the present invention, a speed control assembly for a motor or engine is provided which includes a speed control lever, means for mounting the speed control lever for movement in a first mode to effect speed control of a motor or engine, and means for latching the speed control lever in a position to which it has been moved in the first mode of movement. The assembly further comprises means for mounting the speed control lever for movement in a second mode, different from the first mode, and means responsive to movement of the speed control lever in the second mode for effecting operation of the latching means to unlatch the speed control lever so that it can be moved in the first mode. An electromagnet is provided as the latching means so that the speed control lever can be positively latched in an infinite number of positions. An electric switch is responsive to movement of the control lever in the second mode, the switch being in series with the electromagnet and a power source, such as a vehicle alternator.
A shaft mounts the control lever for rotational movement, the rotational movement being the first mode, and a first portion of the control lever is affixed to the shaft while a second portion of the control lever is linearly reciprocal with respect to the shaft in a dimension perpendicular to the axis of rotation of the shaft, the linear reciprocation providing the second mode of movement of the control lever. The electromagnet preferably comprises an annular member disposed in a plane perpendicular to the shaft axis of rotation, and the latching means further comprises a disc mounted on the shaft for rotation therewith and disposed in a plane perpendicular to the shaft, and adjacent the electromagnet, so that the electromagnet--when energized--exerts a latching force on the disc to hold it in place.
According to another aspect of the present invention, a speed control assembly for a motorized vehicle having a driver's seat and brake means is provided. The assembly includes a hydrostatic transmission for controlling the speed of the vehicle, and having a neutral position; a control lever for actuating the hydrostatic transmission to move it out of and into the neutral position to effect speed control thereby; means for latching the speed control lever in a position to which it has been moved; and means for automatically unlatching the latching mean and returning the hydrostatic transmission to neutral position in response to vacating of the driver's seat by the driver, application of the brakes, or stopping the engine. The latching means comprises an electromagnet and a seat switch and brake switch are disposed in series with the electromagnet and the vehicle alternator to control operation of the electromagnet. Spring biasing means are provided for automatically returning the hydrostatic transmission to neutral.
According to a still further aspect of the present invention, an assembly is provided comprising a control lever operatively connected to a control mechanism for controlling the operation of the mechanism; a shaft connected to the control lever for movement therewith; means for mounting the shaft for rotation about a given axis; and a plate mounted to the shaft for rotation therewith. The assembly further comprises an electromagnet and means for mounting the electromagnet adjacent the plate so that when the electromagnet is energized it holds the plate and prevents rotation of the plate and shaft. The plate preferably comprises a disc disposed in a plane perpendicular to the shaft, and the electromagnet is annular. The shaft is mounted so that it is perpendicular to the plane of the annular electromagnet, and the disc is adjacent and parallel to the electromagnet. A lever means is mounted to the shaft on the opposite side of the electromagnet as the control lever, with the shaft extending through the opening in the annular electromagnet.
It is the primary object of the present invention to provide a simple, effective, and safe control assembly, particular for a hydrostatic transmission. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.